The invented apparatus is designed to meet the requirements of the various container handling operations:
The container must be orientated in order to position it on a transportation vehicle, a boat or another carrier.
The overall dimensions of the container itself must be taken into consideration so as to make allowances for the bulk of the container.
The container should not be excessively tilted in the direction of its longitudinal axis. Excessive tilting, such as those resulting from a bad weight distribution in the container, could prevent the correct loading of the container inside a ship for instance.
Likewise, the axis of the hanging system should remain vertical throughout the container handling operations.
In order to solve the above problems, two types of equipment have been designed.
In the first type of equipment, the container orientation system hangs from the lifting cables and is directly connected to the spreader. This solution has the disadvantage of limiting the hanging pattern to a square in which the diagonal is equal to the width of the spreader, since its overall dimensions cannot exceed the container's dimensions regardless of its orientation. Obviously, the container will remain stable only as long as its center of gravity is located inside that square. This condition being met, the loading operation of the container is generally off-centered and the cables are subjected to various loads which increase the tilting of the container, due to cable elongation. It becomes increasingly difficult to compensate for the excessive tilting by taking up the length of the cables, as the cable loads and cable elongation vary with the container's orientation. Furthermore, it is possible to take up the length of the cables only after the latter have reached a given elongation, and after the container has been put in a wrong position. Finally, the incidental torques overload the cables and the machine's elements by creating cambering and twisting forces within the frame.
In the second type of equipment, the orientation of the system is such that it hangs directly from the machine's frame. By correctly routing the cable on a number of lazy or idle pulleys, it is possible to keep the overall dimensions of the hanging system on the spreader within a rectangle whose length greatly exceeds the width, thus reducing the effects of the above disadvantages but without eliminating them. However, the cables follow the rotating motion of the container, which causes the cable system to become twisted, and it is not possible to obtain an orientation exceeding an angle of 90.degree. on either side of a zero position.